tree-vrp.c (compare_values_warnv): Simplify handling of symbolic ranges by calling get_single_symbol and tidy up.

	* tree-vrp.c (compare_values_warnv): Simplify handling of symbolic
	ranges by calling get_single_symbol and tidy up.  Look more closely
	into NAME + CST1 vs CST2 comparisons if type overflow is undefined.
ada/
	* gcc-interface/decl.c (gnat_to_gnu_entity) <E_Signed_Integer_Subtype>:
	Make same-sized subtypes of signed base types signed.
	* gcc-interface/utils.c (make_type_from_size): Adjust to above change.
	(unchecked_convert): Likewise.

From-SVN: r236548

3 files changed, 30 insertions, 5 deletions

diff --git a/gcc/ada/ChangeLog b/gcc/ada/ChangeLog
index 49c463a..525b89f 100644
--- a/gcc/ada/ChangeLog
+++ b/gcc/ada/ChangeLog
@@ -1,3 +1,10 @@
+2016-05-20  Eric Botcazou  <ebotcazou@adacore.com>
+
+	* gcc-interface/decl.c (gnat_to_gnu_entity) <E_Signed_Integer_Subtype>:
+	Make same-sized subtypes of signed base types signed.
+	* gcc-interface/utils.c (make_type_from_size): Adjust to above change.
+	(unchecked_convert): Likewise.
+
 2016-05-16  Eric Botcazou  <ebotcazou@adacore.com>
 
 	* gcc-interface/decl.c (gnat_to_gnu_entity) <E_Variable>: Do not build
diff --git a/gcc/ada/gcc-interface/decl.c b/gcc/ada/gcc-interface/decl.c
index b51200f..6b6bc07 100644
--- a/gcc/ada/gcc-interface/decl.c
+++ b/gcc/ada/gcc-interface/decl.c
@@ -1814,7 +1814,12 @@ gnat_to_gnu_entity (Entity_Id gnat_entity, tree gnu_expr, bool definition)
       /* First subtypes of Character are treated as Character; otherwise
 	 this should be an unsigned type if the base type is unsigned or
 	 if the lower bound is constant and non-negative or if the type
-	 is biased.  */
+	 is biased.  However, even if the lower bound is constant and
+	 non-negative, we use a signed type for a subtype with the same
+	 size as its signed base type, because this eliminates useless
+	 conversions to it and gives more leeway to the optimizer; but
+	 this means that we will need to explicitly test for this case
+	 when we change the representation based on the RM size.  */
       if (kind == E_Enumeration_Subtype
 	  && No (First_Literal (Etype (gnat_entity)))
 	  && Esize (gnat_entity) == RM_Size (gnat_entity)
@@ -1822,7 +1827,8 @@ gnat_to_gnu_entity (Entity_Id gnat_entity, tree gnu_expr, bool definition)
 	  && flag_signed_char)
 	gnu_type = make_signed_type (CHAR_TYPE_SIZE);
       else if (Is_Unsigned_Type (Etype (gnat_entity))
-	       || Is_Unsigned_Type (gnat_entity)
+	       || (Esize (Etype (gnat_entity)) != Esize (gnat_entity)
+		   && Is_Unsigned_Type (gnat_entity))
 	       || Has_Biased_Representation (gnat_entity))
 	gnu_type = make_unsigned_type (esize);
       else
diff --git a/gcc/ada/gcc-interface/utils.c b/gcc/ada/gcc-interface/utils.c
index 7494065..798048a 100644
--- a/gcc/ada/gcc-interface/utils.c
+++ b/gcc/ada/gcc-interface/utils.c
@@ -1116,7 +1116,14 @@ make_type_from_size (tree type, tree size_tree, bool for_biased)
 	break;
 
       biased_p |= for_biased;
-      if (TYPE_UNSIGNED (type) || biased_p)
+
+      /* The type should be an unsigned type if the original type is unsigned
+	 or if the lower bound is constant and non-negative or if the type is
+	 biased, see E_Signed_Integer_Subtype case of gnat_to_gnu_entity.  */
+      if (TYPE_UNSIGNED (type)
+	  || (TREE_CODE (TYPE_MIN_VALUE (type)) == INTEGER_CST
+	      && tree_int_cst_sgn (TYPE_MIN_VALUE (type)) >= 0)
+	  || biased_p)
 	new_type = make_unsigned_type (size);
       else
 	new_type = make_signed_type (size);
@@ -5111,7 +5118,9 @@ unchecked_convert (tree type, tree expr, bool notrunc_p)
   /* If the result is an integral type whose precision is not equal to its
      size, sign- or zero-extend the result.  We need not do this if the input
      is an integral type of the same precision and signedness or if the output
-     is a biased type or if both the input and output are unsigned.  */
+     is a biased type or if both the input and output are unsigned, or if the
+     lower bound is constant and non-negative, see E_Signed_Integer_Subtype
+     case of gnat_to_gnu_entity.  */
   if (!notrunc_p
       && INTEGRAL_TYPE_P (type)
       && TYPE_RM_SIZE (type)
@@ -5123,7 +5132,10 @@ unchecked_convert (tree type, tree expr, bool notrunc_p)
 				    ? TYPE_RM_SIZE (etype)
 				    : TYPE_SIZE (etype)) == 0)
       && !(code == INTEGER_TYPE && TYPE_BIASED_REPRESENTATION_P (type))
-      && !(TYPE_UNSIGNED (type) && TYPE_UNSIGNED (etype)))
+      && !((TYPE_UNSIGNED (type)
+	    || (TREE_CODE (TYPE_MIN_VALUE (type)) == INTEGER_CST
+		&& tree_int_cst_sgn (TYPE_MIN_VALUE (type)) >= 0))
+	   && TYPE_UNSIGNED (etype)))
     {
       tree base_type
 	= gnat_type_for_size (TREE_INT_CST_LOW (TYPE_SIZE (type)),